Study On Microstructure And Wear Resistance Of Two Kinds Of High Temperature Wear Resistant Surfacing Rollers

Because of its high efficiency and low cost,surfacing technology has become one of the core technologies of green re-manufacturing.Repair and remanufacture of parts with large size,high added value and special performance requirements,such as wear resistance,heat resistance or corrosion resistance,can effectively prolong the service life of these parts,Fe-Cr-C alloy contains a large number of M7C3 carbides and has good wear resistance.However,the carbides in traditional Fe-Cr-C alloys are relatively rough,and they are easy to flake in the process of application,which limits the wide application of the alloys in surfacing welding.In this paper,two kinds of Fe-Cr-C high chromium cast iron fluid-core surfacing materials with different compositions are studied.One is a commercially available flux-cored wire?type:XU524-A?,the other is a wear-resistant alloy with improved composition?adding Cr,C and Mo content appropriately to the XU524-A wire?.In this paper,uses rolls as surfacing objects.Research and development a flux-cored wire,which can be applied in practice and has good comprehensive properties,is studied.The microstructure and phase of the deposited metal layer of welding wire were characterized by means of?OM?X-ray diffraction?XRD?and scanning electron microscopy?SEM?,and the values of the hardness and wear resistance of the alloy layer were tested by means of X-ray diffraction?XRD?and scanning electron microscope?SEM?.The effects of chemical composition,microstructure andthe values of the hardness on the wear resistance of the deposited metal layer were discussed and the wear resistance mechanism of the coating was also studied.The flux-cored wire with the best wear resistance can be obtained by selecting the appropriate welding parameters and technology,which provides a certain basis for the further development of the flux-cored wire.The experimental results show that:?1?the two flux-cored wires are surfaced by submerged arc welding with ZD5-1250 automatic submerged arc welding machine,with HJ107 flux,DC reverse connection,welding current 320A,welding voltage 30V.Surfacing metal without cracks,pores,slag and other defects,good surface formation.?2?the Fe-Cr-C surfacing alloy is mainly composed of M₇C₃ carbide,martensite and austenite.With the increase of C,Cr and Mo content,the values of the values of the micro-Vickers hardness and wear resistance of surfacing alloy layer are increased.?3?with the increase of surfacing layer number,the dilution effect of surfacing wire surfacing alloy gradually weakened,and the microstructure of surfacing layer alloy gradually changed from primary austenite eutectic structure to primary carbides Cr7C eutectic structure.Martensite is the main hard phase.When tempering at 200?,the values hardness of the surfacing layer increases,and when the tempering temperature reaches 400?,the residual austenite is transformed into a high-hardness strip martensite structure.A certain amount of?Fe,Cr?₃C was precipitated inside the strip martensite,the values hardness of the surfacing layer increased?651HV?,and the microstructure with good wear resistance was obtained.After tempering at 600?or800?,the values of the hardness of the carbide with larger particles decreased,and the average values of the hardness of the surfacing layer was 510HVN 311HV.1000?,respectively.The alloy carbide was desolated,which resulted in the secondary hardening of martensite tempering and the increase of the values of the surface hardness.The average values of the hardness of the surfacing layer was 480 HV.?4?compared with the raw material,the improved material increases the value of Cr and C ratio.From the micro-Vickers hardness experiment,it can be concluded that the values of the hardness of the material is higher than that of the XU524-A type wire surfacing alloy,and the wear resistance experiment shows that under the same experimental conditions,the values of the hardness of the material is higher than that of XU524-A type wire surfacing alloy.The wear loss of the modified material is lower and the wear resistance is better,and the wear mechanism is abrasive wear.When the tempering temperature is 200?,the average values of the values of the hardness of the surfacing layer is 585HV.When tempering temperature reaches 400?,the values of the hardness of the surfacing layer decreases when the tempering temperature is 400?.The average values of the hardness of the surfacing layer decreases in turn,and the average values of the hardness of the surfacing layer decreases in turn when the tempering temperature is 200?.The values of the hardness was the lowest at 575 HV,450 HV.1000?,and the average values of the hardness was 380 HV.Therefore,when the temperature is below 800?,the average values of the hardness of the modified material is higher than that of the XU524-A type material,showing excellent wear resistance at high temperature.